CVE-2026-39821
Undergoing Analysis Undergoing Analysis - In Progress
BaseFortify

Publication date: 2026-05-22

Last updated on: 2026-05-22

Assigner: Go Project

Description
The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode("xn--example-.com") incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject "example.com" but permit "xn--example-.com". If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name "example.com".
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Meta Information
Published
2026-05-22
Last Modified
2026-05-22
Generated
2026-05-26
EPSS Evaluated
N/A
NVD
EUVD
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-1289 The product receives an input value that is used as a resource identifier or other type of reference, but it does not validate or incorrectly validates that the input is equivalent to a potentially-unsafe value.
Attack-Flow Graph
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